Capillary device for use in heat pipe and method of manufacturing such capillary device

Abstract

A capillary device (102) for use in a heat pipe in which heat is transferred from at least one evaporation region to at least one condensation region by means of evaporated working fluid is disclosed. The capillary device comprises a body portion defining chambers (108) containing powdered material (110) therein, wherein at least part of the periphery of at least one said chamber is porous to allow flow of condensed working fluid, by means of capillary action, through said powdered material in said chamber when flowing from a condensation region to an evaporation region.

1 . A heat transfer pipe in which heat is transferred from an evaporation region to a condensation region by means of working fluid, the heat transfer pipe comprising:
 a body portion defining a central channel, the central channel extending between and in fluid communication with the evaporation region and the condensation region; and   a capillary structure within the body portion and surrounding the central channel, wherein the capillary structure comprises a plurality of spaced-apart porous protrusions extending radially into the central channel with each protrusion separated from an adjacent protrusion by a gap therebetween;   wherein the heat transfer pipe includes successive layers of metal powder that are located over a donor material and have been melted by an energetic beam, wherein the successive layers at least partially define the plurality of porous protrusions.   
     
     
         2 . A heat transfer pipe according to  claim 1 , wherein each porous protrusion of the plurality of porous protrusions includes a hollow interior and contains unfused metal powder within the hollow interior. 
     
     
         3 . A heat transfer pipe according to  claim 2 , wherein the successive, melted layers of metal powder at least partially define the hollow interiors. 
     
     
         4 . A heat transfer pipe according to  claim 2 , wherein the unfused metal powder is aluminum. 
     
     
         5 . A heat transfer pipe according to  claim 1 , wherein the body portion is formed from aluminum. 
     
     
         7 . A heat transfer pipe according to  claim 1 , wherein each of the gaps extends in a longitudinal direction parallel to the central channel. 
     
     
         8 . A heat transfer pipe according to  claim 1 , further comprising lattice capillary structures positioned in the gaps between the porous protrusions, wherein each of the capillary lattice structures extends longitudinally along a length of the heat transfer pipe between the evaporation region and the condensation region. 
     
     
         9 . A heat transfer pipe according to  claim 8 , wherein the lattice capillary structures do not extend to the evaporation region. 
     
     
         10 . A heat transfer pipe according to  claim 8 , wherein the lattice capillary structures are formed from a plurality of pores which increase in size along lengths of the lattice capillary structures from the condensation region to the evaporation region. 
     
     
         11 . A heat transfer pipe according to  claim 1 , wherein the successive layers at least partially define the body portion. 
     
     
         12 . A heat transfer pipe in which heat is transferred from an evaporation region to a condensation region by means of working fluid, the heat transfer pipe comprising:
 a solid outer body portion;   a porous capillary structure within the outer body portion extending between and in fluid communication with the evaporation region and the condensation region; and   a plurality of vapor flow channels embedded in the capillary structure and extending between and in fluid communication with the evaporation region and the condensation region.   
     
     
         13 . A heat transfer pipe according to  claim 12 , wherein the plurality of vapor flow channels is spaced circumferentially around an interior region of the porous structure. 
     
     
         14 . A heat transfer pipe according to  claim 12 , wherein the heat transfer pipe includes successive layers of metal powder that are located over a donor material and have been melted by an energetic beam, wherein the successive layers at least partially define the porous capillary portion and the vapor flow channels. 
     
     
         15 . A heat transfer pipe according to  claim 12 , further comprising a fluid flow passage formed in the center of the porous capillary structure and extending between and in fluid communication with the evaporation region and the condensation region. 
     
     
         16 . A heat transfer pipe according to  claim 15 , further comprising a region of powder metal between the porous capillary structure and the fluid flow passage. 
     
     
         17 . A heat transfer pipe in which heat is transferred from an inlet chamber to an outlet chamber by means of working fluid, the heat pipe comprising:
 an outer body portion; and   a porous capillary structure positioned within the outer body portion between and in fluid communication with the inlet chamber and the outlet chamber, wherein the porous capillary structure has a porous rigid outer wall and contains unfused powder material.   
     
     
         18 . A heat transfer pipe according to  claim 17 , wherein the inlet chamber and the outlet chamber are divided by the porous capillary structure. 
     
     
         19 . A heat transfer apparatus comprising:
 an evaporation chamber; and   a condensation chamber in fluid communication with the evaporation chamber, wherein heat is transferred from the evaporation chamber to the condensation region by means of working fluid,   wherein the evaporation chamber includes
 an outer cylindrical body that defines an interior volume, 
 a porous capillary structure positioned within the interior volume adjacent an interior surface of the outer cylindrical body, wherein the porous capillary structure defines an interior annular chamber enclosing a layer of unfused metal powder, 
 an elongate escape channel positioned between the interior surface of the outer cylindrical body and the interior annular chamber, wherein the elongate escape channel extends from an interior of the porous capillary structure to a first opening in the porous capillary structure, wherein the first opening is in fluid communication with the interior volume and is formed at an end face of the porous capillary structure, 
 a plurality of spaced-apart circumferential vapor channels interconnected by the elongate escape channel, and 
 a central bore surrounded by the interior annular chamber, wherein the central bore extends between the end face and a second opening of the porous capillary structure to the interior volume, wherein the second opening is in fluid communication with the interior volume and positioned opposite the end face. 
   
     
     
         20 . A heat transfer apparatus according to  claim 19 , wherein the evaporation chamber and the condensation chamber are in the form of a loop heat pipe. 
     
     
         21 . A heat transfer pipe comprising:
 an evaporation region;   a condensation region;   a body portion extending between and in fluid communication with the evaporation region and the condensation region; and   a capillary structure configured to direct working fluid between the evaporation region and the condensation region;   wherein the capillary structure includes successive layers of metal powder that have each been melted by an energetic beam to be secured to one or more other layers of the successive layers.   
     
     
         22 . The heat transfer pipe of  claim 21 , wherein the condensation region includes a condenser plate, wherein the condenser plate defines a donor material, wherein the successive layers of metal powder include a first, melted layer of metal powder disposed on the donor material and a second, melted layer of metal powder disposed on the first layer of metal powder. 
     
     
         23 . The heat transfer pipe of  claim 22 , wherein the first, melted layer of metal powder and the second, melted layer of metal powder define a rigid, porous structure that defines a portion of the capillary structure. 
     
     
         24 . The heat transfer pipe of  claim 23 , wherein the capillary structure extends along an interior surface of the body portion. 
     
     
         25 . The heat transfer pipe of  claim 22 , wherein the condenser plate is an aluminum plate, wherein the first, melted layer of metal powder is aluminum powder, and wherein the second, melted layer of metal powder is aluminum powder. 
     
     
         26 . The heat transfer pipe of  claim 21 , wherein the evaporation region includes an evaporator plate, wherein the evaporator plate defines a donor material, wherein the successive layers of metal powder include a first, melted layer of metal powder disposed on the donor material and a second, melted layer of metal powder disposed on the first layer of metal powder. 
     
     
         27 . The heat transfer pipe of  claim 26 , wherein the first, melted layer of metal powder and the second, melted layer of metal powder define a portion of the body portion. 
     
     
         28 . The heat transfer pipe of  claim 27 , wherein the successive layers of metal powder further include additional layers of melted, metal powder that define the capillary structure, wherein the capillary structure is disposed within the body portion. 
     
     
         29 . The heat transfer pipe of  claim 28 , wherein the capillary structure includes rigid, porous protrusions. 
     
     
         30 . The heat transfer pipe of  claim 21 , wherein the body portion also includes successive layers of metal powder that have each been melted by an energetic beam to be secured to one or more other layers of the successive layers of the body portion.